Applicating Tactile Sensors into Prosthetic Hands

Already infants comprehend the world formally with their sense of touch, everything they touch. Touch the brain provides information about pressure, heat, cold, and material properties of objects. U.S. researchers have now developed an artificial skin that is sensitive to pressure. A first approach to an artificial sense of touch.

Prosthetic Hand Breathrough with Tactile Sensors
Sensitive fingertips for the robot or amputee: US scientists from Stanford University, succeeded with a kind of knob film artificially to recreate the sense of touch.

Man has five senses: he can see, hear, smell, taste, and feel. The sense of touch in human skin is considered to be very sensitive: the skin contains about 100 million sensory cells, which measure the pressure to capture vibrations, heat and cold and feel the material properties of objects. US scientists from Stanford University have succeeded in with a kind of knob film artificially to recreate the sense of touch. You are now presented a first prototype of their artificial skin in the Journal Science.

Circuit generated with inkjet printer Application Tactile Sensors into Prosthetic Hands

“Imagine plastic wrap a piece. On this slide are tiny pyramids made of rubber, they contain small nanometer tubes made of carbon. Pressing the slide the rubber pyramids are pressed together and the nanotubes generate an electrical signal,”chemist Zhenan Bao from Stanford California explains University the principle of artificial tactile. The researchers led by Bao with a second film have stuck this film with the rubber pyramids. On this, they have printed a paper-thin, flexible electronic circuit with an ink jet printer.

Artificial Nerve Pulses measure the pressure

This electronic circuit converts the electrical signals of the pressure-sensitive rubber pyramids in pulse. The principle: The stronger the pressure on the bubble wrap, the faster are the artificial nerve pulses. So is a measure of the pressure.

Prosthetic Hand Breathrough with Tactile Sensors_
The flexible artificial skin looks, before it is placed on the mechanical hand.

For Zhenan Bao, this pressure sensor is only a first step towards to art skin. “So far we have built only small pieces of foil with a few pressure sensors. But our skin contains many sensory cells. So, we have to find out now how many sensors on large area can be made. “And also we want to integrate not only pressure sensors in the skin of our art, but also temperature sensor”, she says confidently.

Light pulses to control light-sensitive proteins

To take advantage of the artificial nerve pulses for a perception in the brain, thinking the chemist about two procedures. ” Either the sensor via an implantable electrode at an appropriate bundle of nerves would be close to. Or to convert electrical signals into optical.

With these light pulses then special light-sensitive proteins are controlled, that it has previously introduced use of genetic engineering in the brain.” This second technique called Optogenetics.

Successfully tested on mice living brain cells

Living brain cells of mice the researchers of at Stanford have tested this procedure successfully University. “We have seen that the brain cells respond in kind on our sensor signals as to the correct sense cells,” Bao reported. “It is the first time that a flexible, skin-like material can detect pressure and can send a signal to a part of the nervous system.”

Monitoring of high-risk patients

The chemist sees a wide application field for their artificial skin. So the bubble wrap could serve to give robots a tactile sense. Bao also remember the monitoring of high-risk patients: “our sensors are extremely sensitive, they’re good for portable electronics.

The sensored foil is applied on the fingertips of the robot hand. It contains small nanometer tubes made of carbon.
The sensored foil is applied on the fingertips of the robot hand. It contains small nanometer tubes made of carbon.

For example you could integrate it in a patch, you simply sticks to the skin and then closely monitor heart rate and blood pressure.” The research team of from Stanford University is by no means alone in an attempt to recreate the sense of touch.

A year ago, two presented studies were done with different prosthetic team. Researchers comes from the United States and Sweden.